Red cell compatibility testing: a perspective for the future

False-negative compatible antiglobulin crossmatches in samples with alloantibodies to cognate red blood cell antigens

BACKGROUND

Patient samples showing a positive indirect antiglobulin test are further tested to identify alloantibody specificity using a panel of phenotypically characterized group O reagent red blood cells (RBCs). Donor RBCs phenotypically negative for the antibody specificity are then serologically crossmatched using an antiglobulin reagent. This latter test is performed to identify any incompatibility due to the presence of undetected minor blood group antibodies and considered an important step in patient safety.

STUDY DESIGN AND METHODS

Samples with well-characterized alloantibodies were intentionally crossmatched against donor RBCs expressing the cognate antigen. In a separate set of specimens, the alloantibody was titered and crossmatched against both heterozygous and homozygous cells.

RESULTS

Thirty-five samples containing 10 common alloantibodies crossmatched against 240 ABO-compatible donor cells phenotypically positive for the cognate antigen showed compatible crossmatches in 89 of 240 (37%). Antibody titering of 12 alloantibodies showed that a titer of 2 or more was required for incompatibility of all homozygous cells and a titer of 8 or more for incompatibility of all heterozygous cells.

CONCLUSION

The antiglobulin crossmatch has a high failure rate (false-negatives) related to antibody titer and donor cell zygosity and is not reliable in interdicting incompatibility due to minor blood group antibodies.

Role of enzyme-treated cells in RBC antibody screening using the gel test: a study of anti-RH1, -RH2, and -RH3 antibodies

The role of enzyme-treated cells (ETCs) in red blood cell (RBC) antibody screening has been the subject of controversy, and its place in the clinical routine remains to be determined. In this work, plasma samples containing anti-RH1 (anti-D; N = 10), anti-RH2 (anti-C; N = 10), or anti-RH3 (anti-E; N = 10) antibodies were studied. The samples were diluted in nonbuffered or buffered normal saline, as well as in a pool of AB plasma samples. Titers and scores were determined by means of the gel test, using the indirect antiglobulin test (IAT) as well as ETCs, with R(0)r, r'r, or r''r test cells. Our results showed that compared to the IAT, ETCs allowed a clearer detection of anti-RH2 and anti-RH3, but not of anti-RH1 antibodies. Based on our study, it is not clear whether the ETC phase of the gel test should be maintained for RBC antibody screening.

Transfusion Medicine: An Overview and Update

The discovery of AIDS in the 1980s and its rapid evolution as a major concern for physicians and their patients have led to many questions about the safety of the blood supply. The attention placed on AIDS has led to new discoveries and technologies to reduce the risk of other transfusion complications such as hepatitis, bacterial contamination, and transfusion-associated graft-vs-host disease. Concerns about blood safety have focused much attention on alternative blood transfusion strategies such as autologous blood, viral inactivation, and artificial blood substitutes. This review describes the transfusion medicine delivery system in the United States, with special emphasis on evolving developments and their implications for the discipline of chemical pathology.

Evaluation and implementation of the gel test for indirect antiglobulin testing in a community hospital laboratory

BACKGROUND

The gel test, developed by Lapierre in 1984, was designed to standardize antiglobulin testing while improving sensitivity and specificity of the method.

PRINCIPLE

Anti-human serum immunoglobulin G (IgG) mixed with Sephadex G100 (gel phase) in a microtube traps red cell-IgG agglutination complexes during migration through the gel in a centrifugation step. Agglutination complexes are visibly detectable at various levels in the microtube as an inverse function of antibody coated on red cells. Unsensitized red cells form a cell pellet at the base of the microtube.

OBJECTIVE

To determine if indirect anti-human globulin testing could be standardized and simplified by replacing the tube test with the gel test without compromising quality or increasing costs.

SETTING

A medium-sized community hospital.

RESULTS

In a blinded retrospective study, we used patient sera (n = 40), which included 10 positive specimens containing 18 known antibodies. Sixteen antibodies were detected and identified with the tube method (1 anti-D and 1 anti-C not detected). By the gel test, 18 antibodies were detected and identified. All negative samples showed 100% concordance. Favorable results were obtained in a nonblinded prospective correlation study (n = 121). Our technologists found the gel test easier to read and more reproducible and reliable than the tube method; they also found increased sensitivity for detecting weakly reacting antibodies. We successfully introduced the gel test into our laboratory as the standard method for indirect antiglobulin testing. Following implementation, improved personnel management was achieved.

CONCLUSIONS

The gel test is a reliable and advantageous method and is appropriate for routine use for detection and identification of alloantibodies in a community hospital transfusion service laboratory.

The transfusion service is an integral and important component of the hospital and should not be outsourced

Hospitals are under increased pressure to decrease operating costs. Hospital-based laboratories, blood banks (transfusion services), increasingly face the potential of being outsourced as hospitals try to survive the current waves of managed care. A number of complicated and unique services are provided by the hospital-based transfusion service and physician. Clinical consultation, complicated immunohematological procedures, apheresis, participation in a complex array of patient-care services, clinical research, ever increasing regulatory issues, and quality assurance activities are only a few of the challenges in today's transfusion medicine environment. This paper will focus on the hospital-based transfusion service, and the transfusion medicine physician, and present arguments as to why this service should remain close to the patient's bedside and not be outsourced.

When less is more: cost-containment in transfusion medicine

The drive to contain the rising cost of medical care provides numerous challenges to blood bankers. Not the least of these is the opportunity to improve quality of care while reducing the cost thereof. This paper explores various cost-reduction strategies, focusing primarily on those applicable to small and medium-sized transfusion services, and demonstrates methods by which they can be implemented to yield improved patient care.